1. Field of the Invention
Embodiments of the present invention relate to an image sensor and a method for fabricating the same. More particularly, embodiments of the present invention relate to an image sensor with an improved light convergence efficiency and a method for fabricating the same.
2. Description of the Related Art
In general, an image sensor refers to a device capable of converting optical signals to electrical signals. A conventional image sensor may include a photoelectric conversion area for converging light, a microlens to increase convergence efficiency of light on the photoelectric conversion area, and a wiring layer to transmit signals to an outer circuit with respect to the converged light on the photoelectric conversion area.
However, a conventional microlens of the image sensor may be formed of silicon oxide or of an organic substance, e.g., a polyimide-based material, thereby exhibiting chromatic aberration. In other words, a refractive index of light transmitted through the conventional microlens may significantly vary with respect to the wavelength of the transmitted light, thereby resulting in non-uniform focal lengths for different color filters. More specifically, chromatic aberration may cause longer focal lengths for longer wavelengths, so that a multi-color image sensor may have a distorted focus. A distorted focus may reduce light convergence on the photoelectric conversion area, thereby weakening and/or distorting generation of a corresponding electrical signal. Improper signal generation by the image sensor may impair light sensitivity and overall operation of the image sensor.